The present invention relates to guide catheters, and more particularly to guide catheters whose shape and/or stiffness can be tailored to a patient through programmed control.
Guide catheters are used routinely in medical procedures, including coronary and other cardiac and vascular procedures. Guide catheters provide a channel through which suitable interventional devices, for example, angioplasty devices, stent delivery catheters, electrophysiology catheters, and so forth, can be introduced, and through which radiographic contrast dye can be injected.
In use, the guide catheter is typically advanced through a valved introducer fitting, up the arteries or veins of the leg or arm, to a desired treatment location (e.g., the heart), where its tip, which is generally soft, is placed against or otherwise near the region to be treated (e.g., the coronary ostium). The catheter should provide good channel integrity and torque response as the catheter is advanced, and should provide good support as the interventional device is advanced. Guide catheters are sold in a variety of preformed sizes and shapes, which are based on years of custom and experienced ranges of patient anatomy. If one guide catheter does not give access or provide enough support, a different guide catheter is typically substituted from a large inventory of guide catheters having various shapes and sizes.
The present invention is directed to a novel guide catheter having electroactive polymer actuators integrated into the guide catheter structure.
According to a first aspect of the present invention, a guide catheter apparatus is provided, that comprises the following: (a) a guide catheter portion that includes a plurality of electroactive polymer actuators disposed along its axial length and (b) a control unit coupled to the actuators and sending control signals to the actuators. Based upon the control signals received from the control unit, the actuators change the shape of the guide catheter portion. If desired, the guide catheter portion can further comprise a plurality of strain gauges for electronic feedback.
The electroactive polymer actuators are beneficially provided over a substantial portion of the fully inserted axial length of the guide catheter portion of the present invention. For example, the electroactive polymer actuators of the guide catheters of the present invention can be disposed along 5%, 10%, 25%, 50%, 75% or more of the fully inserted length of the guide catheter portion.
The electroactive polymer actuators are preferably controllable to provide a desired curvature to the guide catheter portion at each of a plurality of loci along the length of the catheter portion, including xe2x80x9cSxe2x80x9d shaped, in-plane and out-of-plane curves as well as more complex, curvatures.
In some embodiments of the invention, the control signals from the control unit correspond to a user selectable shape for the guide catheter portion, which can be stored, for example, in electronic memory, if desired. In other embodiments, the control signals from the control unit are generated by a shape-generating algorithm based on medical diagnostic imaging data, for example, angiogram data. In still other embodiments, the control signals from the control unit are generated, at least in part, by a manual steering device.
In one preferred configuration, the guide catheter portion comprises a lead module and a plurality of following modules. In this configuration, when each following module reaches a position previously occupied by the lead module, the actuators cause the following module to replicate the orientation that the lead module had when it was at that particular position. Lead module orientation data can be provided, for example, by strain gauges within the lead module. Position data can be provided, for example, by a depth gauge or a linear displacement module.
In some preferred embodiments, at least a portion of the actuators are in tension with one another. This allows, for example, for the catheter to be stiffened after reaching a desired location within the body.
Each electroactive polymer actuator may beneficially comprise (a) an active member portion, (b) a counter-electrode portion and (c) a region comprising an electrolyte disposed between the active member portion and the counter-electrode portion. In preferred embodiments, the actuator further comprises a substrate layer and a barrier layer, with the active member portion, counter-electrode portion and the electrolyte region disposed between the substrate layer and barrier layer. In one specific embodiment, the substrate layer is rolled into the shape of a tube.
Preferred electroactive polymers for the practice of the present invention include polyaniline, polypyrrole, polysulfone and polyacetylene.
In some embodiments, the guide catheter portion comprises a structural element selected from the following: (a) a tubular network comprising at least one metallic filament, (b) a tubular interconnected network of articulable segments, (c) a helical structure comprising at least one metallic filament, and (d) a patterned tubular sheet (e.g., a laser cut tube).
The control unit can comprise, for example, a computer, such as a personal computer. The control unit can be coupled to the actuators in a number of ways, for example, via a multiplexed electrical cable or wireless interface.
According to another aspect of the invention, a method of introducing a guide catheter into a body lumen is provided. The method comprises: (a) providing a guide catheter apparatus like that above, and (b) inserting the guide catheter portion of the guide catheter apparatus into the body lumen while controlling the shape of the guide catheter portion using the control unit. Frequently, the method will further comprise inserting an interventional device through the guide catheter portion in order to conduct a surgical procedure.
One advantage of the present invention is that a guide catheter is provided wherein the shape and/or stiffness of the guide can be controlled along its length.
Another advantage is that hospital inventory can be reduced, because a smaller number of catheter sizes are adequate to fit all patients.
Another advantage is that productivity is increased, because the guide catheters of the present invention provide improved access to complex anatomical locations based on their ability to change shape, and because the support needed during the procedure can be readily adjusted.
These and other embodiments and advantages of the present invention will become apparent from the following detailed description, and the accompanying drawings, which illustrate by way of example the features of the invention.